JPH0247018B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for dynamically writing and reading magnetic information, and more particularly to a method for inspecting the amount of tape on a reel.

It is well known in mechanics that the inertia of a circular object can be determined by applying a known rotational force to the circular object and measuring the rotational distance of the circular object for a certain period of time.

There is a relationship between rotational force and acceleration such that angular acceleration is equal to torque divided by rotational inertia. If the rotating body is initially stationary and the rotational force is constant over time, then the amount of torque applied to the rotating body will give a constant change over a fixed time interval. Different angular accelerations of inertia of different objects are different and therefore the objects move different distances during the reference time interval. Therefore, the rotational distance while torque is applied is inversely proportional to the inertia of the rotating body.

It is known in the art to determine the radius of a tape reel to determine the amount of torque to be applied to the reel motor in a reel-to-reel tape drive.

The tape is moved between the two reels of the tape drive in order to determine the amount of tape on the reel in order to set the appropriate power applied to the motor to provide the correct tape tension. The radius is calculated when However, this radius calculation method cannot be used to detect the amount of tape on a reel before threading the tape through the tape drive in a single reel cartridge.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for determining the amount of tape on a reel without winding the tape onto another reel of a tape drive.

Another object of the present invention is to utilize the relationship between mechanical force and acceleration to determine the amount of tape on a reel stored, for example, in a cartridge.

The present invention uses dynamics to determine the amount of tape on a reel contained within a cartridge, for example, immediately after the cartridge is inserted into a tape drive and before the tape is moved toward another reel of the drive. It utilizes the relationship between force and acceleration.

The method for measuring the amount of magnetic tape on a reel according to the present invention includes, for example, inserting the reel into a tape drive. The inserted reel is then coupled to a reel rotating means. Since the reel is mounted within the cartridge and therefore the tape end remains within the cartridge, a reverse drive is provided to wind the outer loosely wound tape. and,
Forward torque is applied to the reel for a set time interval. Then, the forward rotation distance of the reel is measured. This measured forward rotation distance is used to determine the amount of tape on the reel,
The next motor drive current is set according to this forward rotation distance.

An embodiment of a method according to the invention for determining the amount of tape on a reel in a cartridge includes inserting a cartridge with a reel into a tape drive and coupling the reel to the tape drive. and,
The reel is reverse driven to take up loosely wound outer tape that may cause operational errors. A reel sorting (dimensioning) step is then performed, and a timer is loaded so that this step occurs for a set time interval. The counter is then energized. This counter counts the tachometer pulses applied to the reel drive and indicates the distance the reel has rotated. The reels are then driven forward and the value of the timer is increased. A timer is checked to see if the period of forward driving the reels has expired. After the forward drive period has expired, a flag is set by information from the tachometer as an indication of the amount of tape on the reel and the reel motor is braked from further rotation. Then, the tension test refresh step is entered.
In this step, the reel is driven in a low power reverse drive to rewind the outer loosely wound tape which may cause errors in reel tape tension testing. The amount of torque applied to the drive is set based on the pulse count in the tachometer counter. Also,
In this refresh step, interlayer slip is inspected according to the amount of torque generated by the motor. The amount of tape threading reverse torque produced by the motor is determined according to the number of tachometer pulses in the tachometer counter. Then, the magnetic tape from the cartridge is threaded into the tape drive device while an appropriate amount of reverse torque is applied to the tape so that the tape threading operation is performed smoothly.

Accordingly, embodiments of the present invention are capable of adjusting the torque generated by the motor driving the reel of tape disposed in the cartridge so as to provide the proper torque for the tension testing refresh operation and the tape threading operation. .

Embodiments of the present invention will be described below with reference to the accompanying drawings.

The method according to the invention performs a test function to measure the length (amount) of tape wound on a reel. Because the circumferences of the reels are different, the current applied to the file reel motor needs to be modified during the actual loosely wound tape inspection and tape threading operations into the drive. Following the reel sorting (sizing) test, the motor is driven in reverse direction in pulse mode. Speed control is maintained by a microcode program that increments and decrements a file and reel counter based on the number of pulses from the tachometer. This operation is performed to eliminate slack in the tape within the cartridge. The current to the file reel motor is
It is compared to a given threshold value that would occur if tape slack was removed based on the absence of a tachometer pulse. Inspection of loosely wound tape begins when all tape slack has been removed. The flag set by this reel classification test indicates the type of cartridge loaded according to the amount of tape on the reel. Then, the reverse torque changes depending on the amount of tape on the reel.
given to the reel motor.

The amount of tape wound around the hub of the reel can be determined by using the relationship between force and acceleration. FIG. 1 shows a tape drive to which the method according to the invention can be applied. This tape drive is connected to a drive controller. The motor 2 generates rotational torque using electric power from the power source 1 . Motor 2 rotates reel 4 via clutch 3. The reel 4 has a tape 5 wound thereon a plurality of times and is housed in a cartridge 6.
At the opposite end of the motor 2 is a reel 4 driven by the motor 2.
tachometer 7 that generates pulses based on the rotation of
is installed. The tachometer pulse is
A control device 8 connected to the power source 1 is provided for controlling the power supplied to the motor 2 . A leader block 9 is provided to prevent the ends of the tape from being drawn into the cartridge 6 and to pass the tape 5 through the tape drive for sensing information from the tape 5.

The tachometer pulses generated by the tachometer 7 as a result of the rotation of the reel 4 by the motor 2 are:
It is sent to the control device 8 so that the microprocessor can determine the rotational distance of the reel 4. The relationship between the impulses sent from the power supply 1 to the motor 2 indicates the amount of tape 5 wound on the reel 4. A schematic flowchart of the reel classification method according to the present invention using the relationship between force and acceleration is shown in FIG.

The first step, shown at block 10 in FIG. 2, is to insert the reel into the tape drive. In the example, this step is:
This is done by inserting the cartridge 6 into the tape drive. The second step, shown in block 12, is to start the drive motor 2 of the tape drive.
and coupling the reel 4 to reel rotation means such as a clutch 3. The first operation that occurs when a reel of tape is placed in a reel-to-reel tape drive is to wind up slack tape on the supply reel. Therefore, the next step is to wind up the loosely wound tape on the outside by applying a force in the opposite direction to the drive, as shown in block 14. The difference between reels holding different amounts of tape can be determined by using the relationship between rotational force and acceleration. first,
The reels are set to rest. The torque applied to the motor is assumed to be constant over time.

As shown in block 16, forward torque is applied to the reel for a set time interval by applying a current burst to the supply reel motor. This torque imparts a constant angular acceleration to the reel. The associated angular displacement of the reel is dependent on inertia, which is a function of the amount of tape wound on the reel. Therefore, as shown in block 18, the rotational distance (inertia) of the reel
is measured. Angular displacement can be detected by a preferably digital tachometer coupled to the supply reel motor. The tachometer measures the rotational distance that the reel moves as a result of power being applied to the motor. Power to the motor to provide this torque is provided as the reel unwinds the tape. Therefore, power is only supplied for a very short period of time. Total inertia includes not only the inertia of the tape, but also the inertia of the reel, motor armature, and clutch. The inertia of the motor, clutch, and reel are substantially the same regardless of the amount of tape wound on the reel. As shown in block 20, the measured rotational distance is used as a measure of the amount of tape on the reel. This is because the number of digital tachometer pulses generated is indicative of the distance the reel and motor have rotated.
This number is sensed and directly related to the amount of tape wound on the reel. As shown in block 22, the forward motor drive current is set according to the rotational distance.

Setting the forward motor drive current according to the amount of tape wound on the reel hub is important for two reasons. Firstly, the refresh operation is performed to measure the tension of the tape wound on the reel.Secondly, in the tape threading operation the tape is inserted from the cartridge reel into the tape drive and the tape is driven This is because it is wound on a reel attached to the device. In the refresh operation,
The motor is driven in the opposite direction against the holding end of the tape and the distance of rotation is measured. The rotational distance caused by the driving force is determined by the state of the wound tape. The tension in the wound tape is one factor that determines the corrective action of a reel-to-reel drive. The amount of stress on the tape is a function of the torque produced by the reel drive motor when the tape drive is biased in the winding direction and the tape is held against the winding motion. If the same torque applied to a reel holding many layers of tape is applied to a reel holding only a few layers of tape, the stress on the tape will be so great that it will stretch and potentially break. be. Therefore, the amount of tape wound on the reel must be measured before the refresh operation occurs in order to set the correct amount of torque for the motor to generate the correct tape tension without exceeding stresses that cause stretching or breaking. It must be.

Similarly, during a tape threading operation, a reverse drag current is applied to the cartridge reel to maintain the tape taut during this operation. The amount of stress that can be applied to the tape is a function of the radius of the tape as well as the reverse current applied to the motor. Therefore, it is necessary to set the motor drive current according to the amount of tape on the reel before the reel dimensions are measured by standard methods used in reel-to-reel tape drives.

A typical radius calculation performed by the drive servomechanism can indicate the amount of tape on the reel within the cartridge. However, this can only be done with tape present in the drive between the cartridge reel and the drive reel. Therefore, standard radius calculations can only be performed after the tape has been threaded through the drive. This radius calculation cannot be performed with all tape present on the cartridge reel. As previously mentioned, the radius of the reel, which is a result of the amount of tape on the reel, must be adjusted before the tape is threaded through the drive to set the correct amount of torque to be applied to the drive for refresh and thread operations. need to be measured.

Generally, a method for sensing the inertia of a tape wound on a reel includes the following steps. First, the reel is rotated against the holding end to ensure that the reel is not initially rotating. The reel is then rotated in the direction in which the tape is unwound for a set short period of time. During this set period, the rotation distance is measured. Since inertia is a function of the amount of tape wound on a reel, the rotational distance, which is a function of inertia, is used as a measure of the amount of tape wound on a reel.

A more specific embodiment of the method according to the invention applied to the tape drive of FIG. 1 is shown in FIG. As shown in block 24, the first
The step is to insert the cartridge 6 with the reel 4 and tape 5 into the tape drive. The next step is to connect reel 4 to drive motor 2, as shown at block 26. As shown in block 28,
Reverse direction driving is performed by power supply 1. The reverse drive ensures that the outer loosely wound tape is wound and that the reel itself is not rotating at that time. The next step is as shown in block 30 surrounded by dash-dotted lines.
This is reel classification (dimension measurement) processing. In the preferred embodiment, a portion of this step is performed by controller 8 of FIG. In the reel sorting process, a timer in controller 8 is first loaded, as indicated by block 32. In the preferred embodiment, the timer is set to a value of 48 milliseconds so that motor 2 is powered for 48 milliseconds. Therefore, in the preferred embodiment, the set time for delivering forward impulses is 48 milliseconds. Next, as indicated by block 34, the controller 8
digital tachometer counter is energized. This is to set up a count of pulses from the tachometer 9 which is a measurement of the rotational distance of the motor 2 and reel 4. As shown at block 36, forward drive power is applied to motor 2 under control of controller 8. In the preferred embodiment, 1.36 amps of current is supplied to the file reel motor and the tachometer 9 is
Consists of 250 line optical disk.

Decision block 38 tests to see if the timer has expired. Block 32
As discussed above, the timer is set to 48 milliseconds in the preferred embodiment. If the timer setting time has not expired, block 40
The value of the timer is incremented as shown in . After block 40 has been processed, a test is again made at decision block 38 to see if the timer set time has expired. The operations of blocks 38 and 40 are repeated until the set time has expired. When the timer setting expires, the number of tachometer pulses counted is stored and used to measure the distance of rotation, block 42. If the count value "C" is less than or equal to 4, an error condition is set as indicated by block 44. An error condition occurs when there is a problem with the drive motor or when the reel cannot rotate freely within the cartridge.
When an error condition occurs, further operation with respect to the cartridge is stopped. If the tachometer pulse count is between 4 and 30, the big reel flag is set as shown in block 46. If the number of pulses indicated by the count value "C" of the counter is 30 or more and less than 250, block 48
The standard reel flag is set as shown in . If the number of pulses counted is greater than or equal to 250, an empty reel flag is set, as shown at block 50. The empty reel flag also indicates that the motor has been driven for too long or that too much current has been supplied to the motor. The next step is to dynamically brake the reel motor, as shown in block 52, after determining the tachometer pulse in the counter, as shown in block 42. The process shown in block 30 is now complete, followed by the process shown in FIG.

After tape volume is measured in the reel sorting process, the next step, shown in block 54 of FIG. 4, is to test the tape tension on the reel to determine if a refresh process is required. It is. This process also takes place in the control device 8 in the preferred embodiment. As previously mentioned, a refresh process to compensate for tape tension is only necessary when the cartridge is placed in an environment where the tape expands to relieve the tension on the tape on the reel. A certain tape tension is required for precise movement in reel-to-reel tape drives. Therefore, the tape 5 wound on the outside of the reel and the cartridge 6
To prevent slack from forming between the holding end of the tape passing through the leader block 9 of the reel motor 2, as shown at block 56,
is low power reverse driven by power supply 1. Leader block 9 in cartridge 6 is used to thread tape 5 through the drive. The next step is
The next step is to check the flags set as shown in decision block 58. When it is determined that a large reel is present in the cartridge in the drive, the motor 2 is caused by the power supply 1 to generate a large torque, as shown in block 60. In the preferred embodiment, when producing large torques, the current applied to motor 2 is 4.5
Ampere. When the cartridge is holding a standard reel, the motor receives 2.25 amps of current and produces a low torque, as shown at block 62. Following the processing of blocks 60 and 62, an interlayer slip check is performed at block 64.

Inspection of slip between tape layers is as follows:
This is done by generating a set amount of torque from the motor 2 in the opposite direction that winds the tape 5 onto the reel. In order to test the tension of the tape wound on the reel to be appropriate, the end of the tape 5 is firmly held by a leader block 9 to prevent it from entering the cartridge 6, and the motor 2 is activated. The torque tries to rotate the reel 4 so that the tape 5 is attached tightly. The rotational distance that reel 5 and motor 2 move relative to the holding end of the tape is checked by counting the digital tachometer pulses generated by tachometer 7. Once the reel has moved a predetermined rotational distance and a reel refresh is indicated, the tape is threaded and wound onto a mechanical reel that is released from the cartridge reel, ensuring that the tape tension is maintained correctly. The tape is rewound onto the cartridge reel again. This refresh process is performed only when inspection shows that the tape is wound too loosely on a reel, resulting in interlayer slip. The embodiments of the invention described above ensure that the motor develops the correct torque so that measurements are taken without overstretching the tape or supplying so much current that it pumps out so many reels that interlaminar slip occurs. I guarantee that.

Upon completion of the interlayer slip test step shown in block 64, the set flags are checked again as shown in block 66. This provides a large reverse torque current if the flag indicates a large reel, as shown in block 68, or a small reverse torque current, as shown in block 70, if the flag indicates a standard reel. This is to supply a reverse torque current. The next step, shown at block 72, is to thread the tape from the cartridge reel to the mechanical reel, ie, to the tape drive. According to the present invention, a proper reverse current is supplied so that the tape tension is maintained at a proper level during the tape threading operation. If too much reverse torque is applied to the motor attached to the cartridge reel, the tape will not sag, but will be misaligned or overstretched in the tape drive. If too much reverse torque is applied, the tape will be stretched and broken. moreover,
Excessive reverse current will cause damage to the threading equipment due to abnormal loading.

The method according to the present invention utilizes the relationship between rotational force and acceleration to measure the amount of tape on the reel. Angular acceleration is equal to torque divided by rotational inertia. Reverse drive power is applied to motor 2 as shown in block 28 of FIG.
is initially at rest, and the motor torque is constant with respect to time, so the relationship between force and acceleration is simplified to be a function of rotation angle. A burst of torque is generated from the supply reel motor for a period of time. Different reels have different inertias and therefore different rotation angles.
The reel size (tape amount) can be detected. The tachometer 7 measures the rotational distance during set time intervals and the measured value indicates the rotational inertia. Torque power is applied so that reel 4 begins to unwind the tape. Therefore, the time during which torque is applied to the motor 2 must be very short to prevent the tape 5 from unwinding from the supply reel 4.
In a tape drive, power supply 1 is connected to motor 2.
The cartridge 6 as well as the clutch 3 and motor armature connecting the tape reel 4
Sufficient torque must be provided to rotate the tape 5 and reel 4 within. This total inertia must be used in the force-acceleration equation. In the preferred embodiment, the inertia of clutch 3 and motor 2 was 75 microKgm ² . Further, in this example, the inertia of the tape 5 and reel 4 in the cartridge 6 was 80 microKgm ² for the small reel and 203 microKgm ² for the large reel. Thus, the present invention provides a method for testing the amount of tape contained on a single reel within a cartridge before the tape is threaded onto a mechanical reel via a tape drive.

Note that in the above embodiment, a digital tachometer pulse is used to identify empty reels, standard reels, and large reels, but in order to identify reels of several different sizes (types), The pulse count value may be used to select the number of tachometer pulses required for each reel size (type) and set specific flags to adjust the motor current accordingly for each reel. Also,
The particular current and the particular count pulses provided within the particular time period are also not limiting.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of a tape drive device;
FIG. 2 is a flow diagram illustrating a method according to the present invention for testing the length of a tape wound on a reel; FIG. FIG. 4 is a flow diagram illustrating one embodiment of the method according to the present invention; FIG. 4 is a flow diagram illustrating processing steps subsequent to those shown in FIG. 1...Power supply, 2...Motor, 3...Clutch,
4... Reel, 5... Tape, 6... Cartridge, 7... Tachometer, 8... Control device, 9...
Leader Block.

Claims (1)

[Claims] 1. A method for inspecting the amount of tape wound around a hub of a reel, comprising: holding the free end of the tape wound around the hub; and moving the hub in a direction that opposes the holding of the tape. rotating the hub with a predetermined torque in the direction of unwinding the tape from the hub for a predetermined time interval; and the step of unwinding the tape for a predetermined time interval. measuring the rotational distance of the hub to the reel; and determining the amount of tape on the hub from the measured rotational distance of the hub based on the inertia of the tape and related components. Tape quantity inspection method.